Location-specific characteristics of perivascular spaces as the brain's interstitial fluid drainage system.

Purpose: Brain interstitial fluid plays an important role in the excretion of metabolic waste products into the cerebrospinal fluid through perivascular spaces (PVS). To investigate the normal function of PVS in healthy elderly individuals, we assessed the relationship between PVS and white matter hyperintensity (WMH) on MRI in two locations.

Methods: This study included 296 healthy individuals aged ≥60 years without a history of brain disease who underwent brain MRI. The severities of PVS and WMH were assessed on the location-specific classification in the basal ganglia (BG-PVS) or centrum semiovale (CSO-PVS), and in the deep or periventricular WMH.

Results: The severity of BG-PVS was significantly associated with the severities of deep and periventricular WMHs. In contrast, the severity of CSO-PVS was inversely associated with the severity of deep WMH and was not significantly associated with that of periventricular WMH. The multivariate odds ratios of severe deep WMH for BG-PVS and CSO-PVS were 1.18 (95% CIs: 1.01-1.38) and 0.68 (0.54-0.86), respectively, compared with none deep WMH.

Conclusions: CSO-PVS looks different from BG-PVS in their relationship with deep WMHs. Therefore, CSO-PVS might play an essential role in the normal interstitial fluid drainage system, not as a biomarker of arteriosclerosis.